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282
METALLTJKGY OF IRON AND STEEL.
homogeneity of steel, or of comparing two different samples, is to make the tests on annealed bars. This practice was pursued in Chapter XIII.
SEO. XVe.—Effect of annealing on the physical properties of eye-bar flats.—It does not follow that plates and hars should be annealed to put them into their best condition. On the contrary, the foregoing tests have shown that very little is gained in ductility, white there is quite a loss in working strength, and that it would be better and much cheaper to choose a softer steel in its natural state. Moreover, it must be considered that the bars which have been discussed in the foregoing tables have been small test-pieces which could be treated under fairly constant conditions, and even then the results are far from regular.
TABLE XV-H.
Comparative Tests of Eye-Bar Steel.
	Longitudinal strip ; cut from, near the edge of eye-bar ; natural.					Full-sized eye-bar ; annealed.				
eat number	lastic limit; pounds per square in.	Itimate strength ; pounds per square In.	longation in 8 inches; per cent.	eduction of area; per cent.	lastic ratio ; per cent.	lastic limit; pounds per square in.	.-03 J Itil S-S go* r-i on Am	[ongation in 8 inches ; per cent.	eduction of area; per cent.	lastic ratio ; per cent.
B	8 .	H>	H	8	H	H	p	H	8	H
1	40710	68830	27.CO	47.18	59.1	36500	62100	43.70	32.60	58.8
2	41570	71400	26.25	50.08	58.2	40400	65200	40.00	46.55	62.0
8	89780	69460	25.75	44.81	67.3	88300	63250	41.85	45.95	60.5
4	40880	69400	25.00	48.41	68.9	40600	67100	86.00	45.00	60.5
6	41480	72320	24.50	46.78	57.4	42100	66000	36.60	48.40	64.8
8	41310	73640	23.75	30.54	66.1	83700	67600	45.60	60.00	58.6
7	40370	72060	25.60	40.00	66.0	85400	64700	45.62	61.80	64.7
8	41900	76700	25.75	43.76	54.6	89600	67700	88.43	42.65	58.5
9	41070	69680	27.00	44.33	68.9	85900	65200	40.00	46.40	65.1
AY.	41008	71499	25.62	44.60	67.4	88056	64206	4087	46.54	59.3
These deductions will be corroborated by Table XV-H, which gives the parallel records of pieces-cut from a flat bar in its natural state, and the full-sized eye-bars after annealing. The steel was made and rolled by one of our largest American works. It is plain that-there is a great gain in the elongation, but the reduction of area is unaffected and there is a decided loss in elastic and ultimate strength.
SEC. XVI—-Mefhods of annealing,—A different view of the subject is taken by Grus. C. Henning.* He states that steel is injured
* Tfans. Am. Soc. Mech. Eng., Vol. XIII, p. 572.